前驱体对Pt/C催化剂性能的影响

Effects of the precursors on the performance of Pt/C nano-catalysts

采用浸渍热还原法制备了以Pt(NH3)2(NO2)2和Pt(NH3)4C l2为前驱体的两种聚合物电解质燃料电池用Pt/C催化剂:Pt/C-Pt(NH3)2(NO2)2和Pt/C-Pt(NH3)4C l2.以HRSEM、XRD、循环伏安(CV)和旋转圆盘电极(RDE)等方法研究了前驱体对催化剂的影响.结果表明,Pt/C-Pt(NH3)4C l2晶粒团聚,分布不均,电化学活性较低;而Pt/C-Pt(NH3)2(NO2)2晶粒细小,分布均匀,具有更高的电化学催化活性,是浸渍法制备Pt/C催化剂的有效前驱体材料.而且,Pt/C-Pt(NH3)2(NO2)2对CO氧化和O2还原的高活性主要来自于催化剂比表面积的提高,而对甲醇氧化活性的提高,表面存在更多的(110)晶面也是重要因素.

Two kinds of Pt/C catalysts： Pt/C - Pt （ NH3 ） 2 （ NO2 ） 2 and Pt/C - Pt （ NH3 ） 4 Cl2 for polymer electrolyte fuel cells were prepared by the impregnation method with Pt（ NH3 ）2（ NO2 ）2 and Pt（ NH3 ）4Cl2 as precursors, respectively. HRSEM, XRD, cyclic voltammetry （CV） and rotating disk electrode （RDE） analyses were used to investigate the effects of the precursors on morphology, structure and electrochemical performance of the catalysts. The agglomeration and low performance of Pt particles were observed for Pt/C - Pt（ NH3 ）4Cl2. In contrast, enhanced dispersion of Pt clusters and high electrochemical activity for Pt/C - Pt（ NH3 ） 2 （ NO2 ） 2 were obtained, which indicated Pt（ NH3 ） 2 （ NO2 ） 2 was a better precursor. Results also revealed that for Pt/C -Pt（ NH3 ）2 （NO2）2, the activity enhancement to CO oxidation and O2 reduction reactions resulted from the increase of specific area of Pt clusters, while to methanol oxidation, was mainly due to high percentage of Pt （110） in the surface.